An ass goblin is a mythical creature that emerges from the anus (or ass). Evrey once in a while it emerges, and when it does it lets out a roaring fart which kills a lot of people. The ass goblin was once suspected of killing the dinosaurs.

This is a creature that stalks u in the wee hours of the nite. They live under bridges and have an ass for a face with sharp ass teeth. if u come in contact with one, play dead, it will smell u and crap on your leg. This is its way of showing his territory.

though the other definitions cover wat an assgoblin is, i would like to reveal their history which has been shrouded in mystery for centuries.
They were the spawn of some perverted leprechauns with an anus fetish were condemed by god to be ugly, green and lick/eat ass for the rest of eternity. they have bred over the centuries and are located around the globe. their culture is similar to the culture of people where they live, with slight irish and ass-worshipping rituals thrown in. when found trustworthy, they will befriend humans and sometimes inter-breed. Danny Devito is rumored to be one such half-ass-goblin. i know all of this from an assgoblin i befriended in New York. at the time i was young and knew nothing of the assgoblins inteligence, which is similar to humans, with the exception of annoyingly squeaky voices and anus-licking tendencies. different races of assgoblin are denoted by number of toes

My friend, Ning Nong The Three Toed Ass Goblin lives in New York and has his own line of designer clothes and a pub where crossbreeds(such as Danny Devito) and ass-goblins gather and converse about asses freely